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ext2: fix potential use after free

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commit ecebf55d27 upstream.

The function ext2_xattr_set calls brelse(bh) to drop the reference count
of bh. After that, bh may be freed. However, following brelse(bh),
it reads bh->b_data via macro HDR(bh). This may result in a
use-after-free bug. This patch moves brelse(bh) after reading field.

CC: stable@vger.kernel.org
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pan Bian 2018-11-25 08:58:02 +08:00 committed by Greg Kroah-Hartman
parent 4d5f99ec00
commit 89ed5b72e5
1 changed files with 1 additions and 1 deletions
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2
fs/ext2/xattr.c
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@ -605,9 +605,9 @@ bad_block: ext2_error(sb, "ext2_xattr_set",
}
cleanup:
brelse(bh);
if (!(bh && header == HDR(bh)))
kfree(header);
brelse(bh);
up_write(&EXT2_I(inode)->xattr_sem);
return error;